This invention relates to a metal cutting tool failure event sensor, and more particularly to a metal cutting tool failure monitoring system which indicates an early tool failure event such as breakage of one insert in a multi insert cutting tool or a missing insert.
In metal machining operations such as milling, drilling and reaming where the cutter tool includes a plurality of cutter insert elements arranged circumferentially about a rotary tool, a failure of one cutter element may impose a severe cutting load on the remaining elements leading to increased likelihood of breakage of remaining cutter elements and potential total breakdown of a tool and its specific cutting process. A cutting tool failure event monitoring system which is primarily effective to determine only excessive tool wear or total tool breakdown does not provide a timely signal or indication that perhaps one or more of the individual cutter elements may be broken. A timely signal of a failure event which is a precursor to a potential total tool failure, for example, a breakage of one element in a multi element tool will provide for appropriate remedial cost containment action such as, for example, replacing a broken one of a number of a individual cutter elements on a tool before the broken one causes a cascading action of breakage of the remaining cutter elements, or, replacing a worn cutter element to restore or stabilize the cutting efficiency of the tool or cutting process. Metal cutting tools may comprise a tool holder with plural individual inserts or elements mounted on the holder to perform the cutting process. Other metal cutting tools such as milling cutters may include a generally cylindrical body having a plurality of spiral or helical flutes formed axially along and equally spaced circumferentially on the body. Such flutes may define a plurality of end face sequential cutting edges or surfaces. Failure of a cutting edge, whether it be an insert or flute, in a multi cutting edge tool is difficult to detect in a timely manner, and lack of detection can lead to catastrophic tool failure and deleterious economic consequences.